Oxygen concentration



FIG. 1 is a perspective view of an oxygen concentrator, showing our newdesign;

FIG. 2 is a left side perspective view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a top plan view thereof; and

FIG. 6 is a rear elevational view thereof.

The ornamental design for an oxygen concentrator, as shown anddescribed.